Associations between intestinal lactic acid bacteria species and feeding habits of zoo animals

Aim: Lactic acid bacteria are among the most important bacteria in the intestinal flora and often have beneficial effects on the host. It is known that the bacteria that compose the intestinal flora are influenced by the feeding habits of host animals, but there was a lack of knowledge about lactic acid bacteria. Therefore, also considering the use of select strains as probiotics, this study investigated the relationship between the feeding habits of zoo animals and intestinal Lactobacillaceae species. Methods: Lactic acid bacteria belonging to the family Lactobacillaceae were isolated and identified from the feces of 20 zoo animal species (5 carnivores, 4 herbivores, 7 piscivores, and 4 omnivores). Isolates were identified by the homology of the 16S rRNA gene sequence. In addition, the fecal flora of host animals was evaluated by the 16S rRNA gene amplicon sequencing. Results: The types of Lactobacillaceae species were shown to vary depending on the feeding habits of host animals. Ligilactobacillus salivarius (L. salivarius) and Ligilactobacillus saerimneri (L. saerimneri) were isolated from the feces of carnivores. Whereas Ligilactobacillus equi (L. equi), Limosilactobacillus gorillae, Ligilactobacillus hayakitensis and L. salivarius were isolated from the feces of herbivores. These Lactobacillaceae species were not found in the feces of piscivores. Instead, Enterococcus were frequently found in piscivores. The fecal flora also differed according to the feeding habits of host animals; at the phylum level, Bacillota was predominant in all animals; on the other hand, herbivores tended to have a higher proportion of Bacteroidota than carnivores, and piscivores tended to have a higher proportion of Proteobacteria. Conclusion: Lactic acid bacteria differ among animal species in a manner dependent on the hosts' feeding habits.